1. Technical Field
The present application relates to an image capturing processor which can obtain information about the surface topography of a translucent object or any other substance which is usually difficult to observe using only light intensity (luminance) information, and also relates to an endoscope which can be used to observe the surface of an organ.
2. Description of the Related Art
An image is captured through an endoscope by illuminating the wall surface of an organism's organ which is covered with a mucosa with light. When an organ is observed through an endoscope, not only a variation in the surface color of the object but also its micro-geometric surface texture need to be inspected. However, as will be described later, it is difficult to capture such a micro-geometric surface texture of the object based on the shades of the light intensity when the object is observed through an endoscope. For that reason, some blue pigment liquid such as an indigo carmine solution is sprinkled onto a mucosa as the object and the surface of the mucosa, of which the grooves are filled with such a blue pigment liquid, is observed based on its light intensities.
According to such an observation method, however, some liquid needs to be sprinkled onto the mucosa, and therefore, the object may bleed, the mucosa may change its color, and many other problems will arise. On the other hand, when a so-called “capsule endoscope” which shoots an internal body tissue in water is used, it is impossible to sprinkle any liquid onto the mucosa in the first place.
Thus, to overcome these problems, some people have proposed a polarization endoscope which uses a polarized light source and a polarization image sensor (see JP 2009-246770 A1, JP 2010-104421 A1, JP 2012-24140 A1, JP 2010-82271 A1, for example).
Meanwhile, a polarization image sensor which uses a wire grid polarizer made of aluminum is disclosed by Viktor Gruev, Rob Perkins, and Timothy York in “CCD Polarization Imaging Sensor with Aluminum Nanowire Optical Filters”, 30 Aug. 2010/Vol. 18, No. 18/OPTICS EXPRESS pp. 19087-19094.